After years of development, the light-emitting diode (LED) has been widely applied in different fields like display, indication, back light and lighting. Conventional P-type III-V group semiconductor material has poor current spreading performance. To enable even injection of current into the light-emitting layer, a current spreading layer is added over the p-type material layer. Among many materials as current spreading layer (TCL) to improve the current spreading effects like ITO, CTO, InO and ZnO, the ITO (Indium Tin Oxide) is most widely applied. The ITO film refers to indium tin oxide semiconductor transparent conducting film, and the ITO meets two index requirements, namely low resistivity and high light transmittance. Compared with other transparent semiconductor conducting films, ITO has good chemical stability, heat stability, good adhesiveness to substrate and pattern processing property.
With reference to FIG. 1, a conventional light-emitting diode structure, comprising a substrate 100, a first confinement layer 101, a light-emitting layer 102, a second confinement layer 103, a current spreading layer 104, a P electrode 105 (comprising a first metal barrier layer 107, a second metal barrier layer 108 and a metal surface layer 109) laminated from bottom to up, an N electrode 106 (comprising a first metal barrier layer 110, a second metal barrier layer 111 and a metal surface layer 112) over the exposed surface of the first confinement layer 101. However, poor adhesiveness of the current spreading layer and the P electrode is easily to cause film stripping between them, which may influence LED reliability and product yield.